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A quantum mechanical model is used to derive a generalized Landau-Lifshitz equation for a magnetic moment, including fluctuations and dissipation. The model reproduces the Gilbert-Brown form of the equation in the classical limit. The…

Materials Science · Physics 2009-11-07 A. Rebei , G. J. Parker

A general method of solving the drift kinetic equation is developed for an axisymmetric magnetic field. Expanding a distribution function in general moments a set of ordinary differential equations are obtained. Successively expanding the…

Plasma Physics · Physics 2023-04-11 Jeong-Young Ji , Eric D. Held , J. Andrew Spencer , Yong-Su Na

Hamiltonian models for the first three moments of the drift-kinetic distribution function, namely the density, the fluid velocity and the parallel pressure, are derived from the Hamiltonian structure of the drift-kinetic equations. The link…

Plasma Physics · Physics 2015-10-13 Maxime Perin , Cristel Chandre , Emanuele Tassi

Expressions of polarization and magnetization in magnetically confined plasmas are derived, which include full expansions in the gyroradius to treat effects of both equilibrium and microscopic electromagnetic turbulence. Using the obtained…

Plasma Physics · Physics 2022-06-01 H. Sugama , S. Matsuoka , M. Nunami

In the spirit of analog models of and for general relativity, we explore the isomorphism between the equations of linearized turbulent fluid flow and those of the linearized form of GR, gravitoelectromagnetism. The correspondence between…

General Physics · Physics 2009-02-07 H. E. Puthoff

A central problem of turbulence theory is to produce a predictive model for turbulent fluxes. These have profound implications for virtually all aspects of the turbulence dynamics. In magnetic confinement devices, drift-wave turbulence…

Plasma Physics · Physics 2020-07-01 R. A. Heinonen , P. H. Diamond

We study the magnetization dynamics of thin-film magnetic elements with in-plane magnetization subject to a spin-current flowing perpendicular to the film plane. We derive a reduced partial differential equation for the in-plane…

Mesoscale and Nanoscale Physics · Physics 2016-10-26 Ross G. Lund , Gabriel D. Chaves O'Flynn , Andrew D. Kent , Cyrill B. Muratov

We describe a formal procedure to obtain and specify the general form of a marginal distribution for the Lagrangian acceleration of fluid particle in developed turbulent flow using Langevin type equation and the assumption that velocity…

Statistical Mechanics · Physics 2007-05-23 A. K. Aringazin , M. I. Mazhitov

We consider fluctuations of the dissipated energy in nonlinear driven diffusive systems subject to bulk dissipation and boundary driving. With this aim, we extend the recently-introduced macroscopic fluctuation theory to nonlinear driven…

Statistical Mechanics · Physics 2013-10-29 P. I. Hurtado , A. Lasanta , A. Prados

The relativistic fluid is a highly successful model used to describe the dynamics of many-particle, relativistic systems. It takes as input basic physics from microscopic scales and yields as output predictions of bulk, macroscopic motion.…

General Relativity and Quantum Cosmology · Physics 2015-06-25 N. Andersson , G. L. Comer

Equations governing the flow of a polar fluid, with pressure-dependent Newtonian viscosity, through a variable-porosity medium are developed. Averaged equations are obtained using intrinsic volume averaging. A drag function is introduced to…

Fluid Dynamics · Physics 2025-12-04 M. H. Hamdan , D. C. Roach

We develop stochastic mixed finite element methods for spatially adaptive simulations of fluid-structure interactions when subject to thermal fluctuations. To account for thermal fluctuations, we introduce a discrete fluctuation-dissipation…

Mesoscale and Nanoscale Physics · Physics 2023-02-28 Pat Plunkett , Jon Hu , Chris Siefert , Paul J. Atzberger

A new representation of electromagnetic gyrokinetic Vlasov-Maxwell theory is presented in which the gyrocenter equations of motion are expressed solely in terms of the perturbed electric and magnetic fields. In this representation, the…

Plasma Physics · Physics 2020-09-25 Alain J. Brizard

Fluctuation dynamos are generic to turbulent astrophysical systems. The only analytical model of the fluctuation dynamo, due to Kazantsev, assumes the velocity to be delta-correlated in time. This assumption breaks down for any realistic…

Astrophysics of Galaxies · Physics 2015-07-22 Pallavi Bhat , Kandaswamy Subramanian

Recently, an increasing interest in astrophysical as well as laboratory plasmas has been manifested in reference to the existence of relativistic flows, related in turn to the production of intense electric fields in magnetized systems.…

Plasma Physics · Physics 2011-02-22 Alexei Beklemishev , Piero Nicolini , Massimo Tessarotto

Turbulence with a large magnetic Reyonolds number, generically leads to rapidly growing magnetic noise over and above any mean field. We revisit the dynamics of this fluctuating field, in homogeneous, isotropic, helical turbulence. Assuming…

Astrophysics · Physics 2007-05-23 K. Subramanian

In this paper, a generalized Brownian motion model has been applied to describe the relative particle dispersion problem in more realistic turbulent flows. The fluctuating pressure forces acting on a fluid particle are taken to be a colored…

Fluid Dynamics · Physics 2015-08-07 Bhimsen Shivamoggi

A conservative formulation of the drift-reduced fluid plasma model is constructed by analytically inverting the implicit relation defining the polarisation velocity as a function of the time-derivative of the electric field. The obtained…

We consider the sloshing problem for an incompressible, inviscid, irrotational fluid in an open container, including effects due to surface tension on the free surface. We restrict ourselves to a constant contact angle and seek…

Analysis of PDEs · Mathematics 2017-06-21 Chee Han Tan , Christel Hohenegger , Braxton Osting

A physically-based method to derive well-posed instances of the two-fluid transport equations for two-phase flow, from the Hamilton principle, is presented. The state of the two-fluid flow is represented by the superficial velocity and the…

Fluid Dynamics · Physics 2021-04-07 Alejandro Clausse , Martin Lopez de Bertodano